Body for rockets and rocketlike vehicles



Feb. 3, 1953 F. KRAEMER BODY FOR ROCKETS AND ROCKETLIKE YEHICLEZS Filed Sept. 28, 1950 2 SHEETSSHEET l 2 SHEETS-SHEET 2 Filed Sept. 28, 1950 grwc/wto'a Fricz Kram'ner lll Patented Feb. 3, 1953 BODY FOR ROCKETS AND ROCKETLIKE VEHICLES Fritz Kraemer, Huntsville, Ala., assignor to the United States of America as represented by the Secretary of the Army Application September 28, 1950, Serial No. 187,339

(Granted under Title 35, U. S. Code (1952),

see. 266) 8 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates in general to rockets and rocket-like vehicles and in particular to a novel means for strengthening and stiffening the body or fuselage of those vehicles.

The design of present rockets and rocket-like vehicles, such as turbojets and ram-jets, is such that the structure of the body may be considered to be a cylinder without any interior strengthening structure. The size of these rockets or rocket-like vehicles is such that the fuel containers therefore can be built as single units and mounted within the vehicle in the usual and well known manner. In order to improve the flight efficiency and range of rockets or rocket-like vehicles, larger rockets and twoand three-stage rockets will be built in the future. Single-stage rockets will be used for heavy payloads and short ranges and twoand three-stage rockets will be built for large range. It is anticipated that single-stage rockets for heavy payloads and multistage rockets for large range will be built that will have takeoff weights of 120 to 150 tons. It is further anticipated that the weight of the fuel will be approximately 100 tons and more for the first stage, or booster stage.

During flight, this fuel weight will produce a load of 200 to 300 tons in the longitudinal axis of the missile due to the acceleration of the missile by the thrust of its motor. This acceleration amounts to about six times the earths acceleration. For such loads in connection with the control forces, the conventional structure of the missile body can no longer be used since it would become too heavy and not stiff enough. The fuel containers would also become too heavy. The same holds true for the fastenings joining the containers to the rocket. All these weights together would be too great to allow the rocket to have a noticeable efficiency. For the design of efiicient missiles the ratio of the empty weight of the rocket proper to its fuel weight has to be made as low as possible. Furthermore, the mass forces and the air forces acting on the missile during flight increase more rapidly with scaling up a missile than does its stiffness. Rockets of this size have to be built extraordinarily stiff if noticeable deformations of the body are to be avoided because these deformations themselves produce additional air forces. The usual, conventional type of design does not prevent these increased deformations of large rockets unless the empty weight is increased by the use of thicker material. On the other hand, rockets with a high body stiffness are controlled more easily and with greater hitting accuracy and, therefore, with fewer requirements on the steering device than those rockets that become deformed during the flight due to the acting forces. At the same time, any design of the structure which gives high body stiffness saves weight of the structure as well as of the control mechanism.

According to my invention, a new missile structure is made possible which deviates from the conventional design and results in low empty weight and high stiffness. There are several parts of my invention which may be used individually or in combination, and which entail several advantages.

One part of my invention consists of one or more concentric cylinders arranged inside the body of the missile with their axes parallel to the missile longitudinal axis. These cylinders are connected with the hull and with each other by members or partitions which are able to transmit loads from one part to the other. This inner structure receives the shear stress if bending forces act on the missile body due to the mass, the air, and the control forces by the rudders and fins.

Since the stiffness of concentrically arranged cylinders in the interior of the body connected with each other and with the hull by force carrying members is greater than the stiffness of a single hull of the same weight, material and weight can be saved for the same amount of stiffness.

A special feature of my invention is that the inner cylinder or cylinders and also the partitions can be used as supports or members for fastening all the necessary accessories and auxiliaries of the missile. My invention offers the advantage that a place for fastening these accessories is available throughout the entire missile body wherever they are needed so that an individual support can be dispensed with and the item placed at the most convenient place. This is also true for the fuel containers, if used, which can be fastened to the cylinder, to the partitions, or even inside the cylinder and they may be built either in metal or in rubber, whichever is deemed most suitable for the purpose. For large amounts of fuel it is of great advantage to have the fuel volume divided and stored in several smaller containers. These smaller containers can be built more economically and cheaper than one large container. Stress on the fastening means is re- Limb duced and distributed more uniformly over the structure of the missile.

Another part of my invention consists of inserting two walls or a multiple thereof in planes at right angles to the longitudinal axis of the missile. The connections between these walls or heads and the missile hull is liquid tight, thus forming one or more compartments which are used for storing the fuel without individual cont-ainers. When using liquid tight seams or connections the conventional containersfor the fuel, as explained above, are dispensedwith and the weight of the single containers and of the members for fastening them within the missile body are eliminated. These heads are not only connected to the hull but also to the ends of the cylinder or cylinders and the members or partitions within the hull by seamswhich are able to carry loads. Thus, the load on the heads due to the fuel weight or the weight of the accessories is taken by the cylinders and the partitions and transmitted to the hull whereby the head is re lieved of forces and the load is distributed very uniformly to the hull. lhus, the heads willsupport very little load and can be made very light. On the other hand, the heads improve the stiffness of the hull and of fuselage structure.

Another part of my invention is to give the heads which form the upper and lower parts of the accessory and fuel compartments a special curved shape whereby the structure is further stiffened and strengthened, the entire length of the missile reduced and other advantages obtained.

It is, therefore, an object of my invention to provide a body for a missile: which combines the advantages of high stiffness and low empty weight.

It is a further objectof my invention to'v stiffen and strengthen the body of a missile by the use of inner cylinders in the longitudinal axis of the missile and by' joining members between said cylinders and the hull.

It is a still further object of my invention: to eliminate the conventional fuel containers and fastening means in a missile by theuse of heads at right angles to the missile longitudinal axis in connection with stifiening structures comprising cylinders and joining members;

Fig. 1 is an elevation in section of a rocket showing the interior thereof stifienedi and strengthened.

Fig. 2 is a section view of the rocket of Fig. l on lines 2-2 showing the members joining the cylinder and the hull.

Fig. 3 is a section view of a rocket showingan alternative arrangement of the joiningimembers.

Fig. 4 is a partial elevation in section of a rocket showing two cylinders dividing a fuel compartment.

Fig. 5 is a section view on lines 5+-5 of Fig: 4'.

Fig. 6 is a section view through a section of a rocket showing two inner cylinders and an alternativearrangement of the joining members.

Fig. 7 is an elevation in section of a rocket having a-two-stage body.

Figs. Sand 9 are partial elevations in section of a' rocket fuel tank showing the direction of forces upon the head of the tank during periods of acceleration.

Figs. 10 and 11 are views partially in section of a rocket tank showing the path of the fuel flow when being discharged from the container.

In Fig. l the rocket has two compartments which may beeither fuel or instrument compartments shown generally as U and L divided by the bottom head 8 of the upper compartment and the top head 3 of the lower compartment. The ends of cylinder. 9 are connected with top head H3 and bottom head 8 and, as can be seen from Fig. 2, the cylinder is connected with hull l2 by members 6. The ends of cylinder '5 are connected with top head 3 and bottom head 4 and the cylinder is'connected to hull 42 in a manner similar to the connection of cylinder 9 to the said hull. The ends of the members 6 are also connected with top head I!) and bottom head 3 of the upper compartment and with top head 3 and bottom head 4 of the lower compartment.

The members 5 may be arranged radially as shown-in Fig. 2. As an "alternative arrangement the members may be formed as a series of profiles in a corrugated manner or as a continuous series of joined Vs as shown in Fig. 3, with the apexes or points thereof in contact with and secured to the hull I2; The members 6 transmit longitudinalforces from the inside of the missile t0 the-hull and vice versa. Thus, in case of a fuel compartment, the stress is distributed. The members 6 also transmit lateral forces-from: the inside of the missile to the hull and viceversa; thusdistributing the stresses and dampening the motion of the fuel during flight. The number of members is unlimited but the proper number can be determined from the size of the missile and the stiffness desired in accordancewithstress analysis. The cylinder or cylinders and. the members or partitions may be provided with holes orother suitable openings which; in case of afuel compartment, allow a flow of the fuel: inside the compartment, thus using; theentire space between the hull and the heads-as one uniformcompartment.

Figs. 4 and 5 show two. cylinders 5a and 5b inserted in the hull and connected to each. other and to the hullby members 8. Additional members can be arranged in the centerof the innermost cylinder as shown in Fig; 6. The number of cylinders may be increased according tothe special needs and'demands of a particular application. The cylinder' or cylinders and the members or partitions may again be provided with holes or other suitable openings which allow a flow of the fuel inside the compartment, thus using the entire space between the hull and the heads as one uniform compartment.

Figure 7 shows a two stage rocket body, the lower unit of whichwill now be described. Reference character I2 indicates the hull or skin of. the lower stage. Arranged in concentric relation with the hullare cylinders 5 and 5a which are connected to the: hull by the usual joining members and by top heads 3 and 3a and bottom heads 4 and 4a, to form the compartmentsU and L of the lower stage of the rocket. Outlets 9 for fuel discharge-are shown in thelower portion of lower head 4 and any suitable connection may be made" thereto to conduct the fuel to the rocket pumping system. The structure of the upper stage is identical but is reduced in size.

The compartment-forming heads, especially the bottom head i, are shaped so that the curvature or convex. side faces the inside of the com.- partment. Thus, the seams between the bottom head and the hull will be stressed only by shearing forces instead of by tension forces and the deformation of the bottom head under load will cause the seam of the head to be pressed against the hull. Thus a further increase in the strength of the missile. body is obtained.

Fig. 8 indicates the behavior under longitudinal forces of a conventional bottom head with its convex surface toward the outside.

Fig. 9 indicates how the bottom head with its convex surface toward the inside of the compartment, in accordance with this invention tends to press the ends of the head against the hull thus tightening the seam when longitudinal forces are applied thereto.

By the use of my invention a considerable reduction of the empty weight of the rocket body is achieved. No separate fuel containers are needed. Only top and bottom heads are required to form the fuel compartment or compartments, together with the hull which is existent in any case. Since the fuel weight acting on the bottom head is largely transferred to the cylinder or cylinders arranged in the interior of the fuel compartments and to the members and carried over to the hull of the missile, the bottom head of the fuel compartment or compartments will be divided into a large number of weight carrying areas whereby the force per load carrying member is reduced and the metal can, therefore, be made very light, saving weight for this part. By the very uniform distribution of the fuel load over the hull, the hull can stand more stress and, can be made lighter than a normal hull.

Since the stiffness of concentrically arranged cylinders in the interior of the fuel compartment or compartments connected with each other and the hull by force carrying partitions or members is greater than the stiffness of a single hull of the same weight, material and weight can be saved for the same amount of stiffness.

Besides the saving of weight through this invention, a very stiff and strong design and structure of the missile body are made possible. Through the use of my invention, the best possible uniform distribution of the fuel load is,

secured by carrying the load to the cylinders, the bottom head, and the hull. Furthermore, the strength of the seams between the heads and the hull is increased through their shape, which means a further improvement of the stiffness of the whole body.

The arrangement of the cylinders in the interior of the fuel compartment allows a very easy connection of the different stages in case of a multi-stage rocket. Because of the strength and stiffness provided by the cylinders and the members and the top head of the first stage, the body of the next stage can be placed on top of one or more of the inner cylinders and connected by any conventional means l5 as shown in Fig. '7. I

The forces and loads of the upper stage will be applied only to the cylinder or cylinders and thus be transferred to the hull. No additional reinforcement of the cylinders or the members will be necessary. No special arrangements for the placing of the next stage on the preceding stage are needed so that the connection between the stages is made possible with a minimum of structural weight.

The shape of the heads facing the inside of the containers provides some further advantages which are of considerable importance for the design of rockets and rocket-like vehicles.

The accessibility of both sides of the seam from the outside of the body makes it easy to connect the heads with the hull, as shown in Fig. 9. Any method of joining may be used, especially the electric seam-welding method, and no special machines or methods are required.

The lowest point of the fuel compartment is 6. situated along the entire circumference of the bottom head. Therefore, the fuel discharge can be made at the most suitable point of the circumference. In Fig. '7 two outlets 9 are shown. Since the shape of the heads creates an empty space between the compartment and the body, this space can be used for locating accessories if desired.

Furthermore, the so-called bath-tub vortex" shown in Fig. 10 in the discharged fuel is avoided. This vortex prevents the fuel from flowing at the required rate especially at the end of the discharging period which causes a sharp decrease of the thrust of the rocket or even its complete failure. Efforts have to be made in the conventional design to avoid this vortex. Through the use of my invention, no vortex can occur because the direction of the average streamline of the discharging fuel goes from the center of the container towards the outer wall as shown in Fig. 11, thus reducing the rotational velocity component according to the physical law of the constancy of energy. This rotational velocity component is finally reduced to zero on its way to the outlet by friction on the members, the bottom head, and on the hull.

The particular embodiment shown is for illustrative purposes only. Many modifications will readily suggest themselves to those skilled in the art and the invention is therefore not to be deemed as limited except within the scope of the appended claims.

I claim:

1. A body for rockets or the like including the walls of the rocket hull, inner cylinders and partitions disposed therein and cup-shaped top and bottom heads secured to the hull and to the ends of the cylinders and partitions with the convex surface of the heads facing each other.

2. In a rocket or the like having a hull, a cylinder disposed within and in longitudinal alignment with said hull, a member disposed between said cylinder and said hull, additional members disposed at right angles one to the other within the said cylinder, the first mentioned member comprising a continuous series of Vs, and cup-shaped top and bottom heads secured to the top and bottom of the said cylinder.

3. In a rocket or the like having a hull, a fuel compartment comprising a cylinder disposed within and in longitudinal alignment with said hull, partitions longitudinally disposed between said cylinder and said hull, additional partitions longitudinally disposed Within said cylinder, cupshaped top and bottom heads secured to the top and bottom of the said cylinder, the convex surfaces of the heads facing each other, and outlets from said fuel compartment disposed in the outer periphery of the said bottom head whereby the fuel flow vortex is reduced.

4. A fuel compartment for a rocket or the like having a cylindrical hull, a plurality of cylinders of unequal diameters disposed within and in concentric relation with each other and with said hull, force transmitting members between the said cylinders and between the cylinder having greatest diameter and said hull, additional force transmitting members within the cylinder of least diameter, cup-shaped heads secured to the tops and bottoms of the said cylinders and to the said hull, and fuel outlets in the lower cup-shaped head, said outlets disposed in the outer periphery of the said lower cup-shaped head,

5. A body for rockets or the like comprising external walls, partitions, and at least one cylinder disposed: longitudinally therewithin, a cu shaped top head and a cup shaped bottom head? fixed to the said cylinderand to the said partitions and further fixed at the outer periphery thereof to the, Said walls, the convex sides of the respective heads facing each other;

6.. A body for'rocketsaor the like comprising-external walls, partitions disposed within said walls, at least one cylinder disposed within and in longitudinal alignment with said walls; a top and bottom; member secured. to the said Walls and, to the said partitions in spacedplanes at right angles to the longitudinal axis of the said: walls, saidv members having substantially theuforrn of a bowed disc fixed at the periphery thereof to the said Walls; the convexsides of; the respective members facing each other;

7'. The invention according to claim 6 wherein at least some of said partitionscomprise a con.- tinuous series of s. v

8% 8. The; inventionv according to-claim 7 wherein thetsaid series of Vs is disposed between the said cylinder and the said walls.

FRITZ KRAEMER.

REFERENCES CITED The following references are of record in the file of this patent:

10 UNITED STATES PATENTS Number Name Date- 47,544 Hotchki'ss' May 2, 1865 622,479 Isham Apr. 4', 1899 F 722,346 Emery Oct. 13, 1904 FOREIGN PATENTS Number Country Date.

3,468 Great Britain of 1898 637,043 Germany Oct. 19,. 1986 20 866,598 France May 26, 1941 

